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| United States Patent |
5,760,669
|
|
Dangler
, et al.
|
June 2, 1998
|
Low profile inductor/transformer component
Abstract
A low profile, low cost, high performance inductor/transformer component
having a wire coil within a core set which is disposed at least partially
within a recess in a header. The header includes projections extending
from it which form terminals when wire leads from the coil are wrapped
around them.
| Inventors:
|
Dangler; Willard K. (Yankton, SD);
Bodenstedt; Steven R. (Yankton, SD);
Waring; Bruce R. (Yankton, SD)
|
| Assignee:
|
Dale Electronics, Inc. (Columbus, NE)
|
| Appl. No.:
|
736333 |
| Filed:
|
October 23, 1996 |
| Current U.S. Class: |
336/65; 336/83; 336/192; 336/212 |
| Intern'l Class: |
H01F 027/06; H01F 027/29 |
| Field of Search: |
336/65,192,83,212
|
References Cited
U.S. Patent Documents
| 3510858 | May., 1970 | Flanagan | 336/83.
|
| 3603917 | Sep., 1971 | Owen | 336/65.
|
| 3859614 | Jan., 1975 | Reithmaier | 336/192.
|
| 3990030 | Nov., 1976 | Chamberlain | 336/65.
|
| 4427961 | Jan., 1984 | Suzuki | 336/83.
|
| 4498067 | Feb., 1985 | Kumakawn et al. | 336/65.
|
| 4516103 | May., 1985 | Arnold | 336/65.
|
| 4754370 | Jun., 1988 | DeTizio et al. | 336/65.
|
| 4769625 | Sep., 1988 | Meindl | 336/83.
|
| 4888571 | Dec., 1989 | Kobayashi et al. | 336/83.
|
| 5015981 | May., 1991 | Lint et al. | 336/65.
|
| 5212345 | May., 1993 | Gutierrez.
| |
| 5359313 | Oct., 1994 | Watanabe.
| |
| Foreign Patent Documents |
| 60-208808 | Oct., 1985 | JP | 336/65.
|
| 1407501 | Sep., 1975 | GB | 336/83.
|
Other References
AT&T Improved Coil Bobbin--Dickens, et al.
Technical Digest No. 76, Mar. 1988, pp. 19 & 20, 336-192.
|
Primary Examiner: Kozma; Thomas J.
Attorney, Agent or Firm: Zarley, McKee, Thomte, Voorhees, & Sease
Parent Case Text
This is a continuation of application Ser. No. 08/349,038 filed on Dec. 3,
1994, now abandoned.
Claims
What is claimed is:
1. A low profile electronic component comprising:
a header having a recess formed within said header, said header forming a
plurality of projections extending from said header and being generally
parallel to said header, said projections being formed from the same
material as the header;
first and second opposing core members forming a core set, said core set
being at least partially disposed within said recess;
a pre-wound coil disposed at least partially within said core set such that
the pre-wound coil is insertable into the first core member and held in
place by the second core member, said pre-wound coil having a plurality of
wire leads; and at least one of said wire leads being wrapped around one
of said projections to form a conductive surface on said projection to
form a component terminal.
2. The low profile electronic component of claim 1 wherein said header and
said core set are bonded together with an adhesive.
3. The low profile electronic component of claim 1 further comprising a
layer of solder disposed over at least a portion of said component
terminal.
4. The low profile electronic component of claim 1 wherein said pre-wound
coil is comprised of at least two wires electromagnetically coupled
together to form a transformer.
5. The low profile electronic component of claim 1 wherein said pre-wound
coil includes a wire coil to form an inductor.
6. The low profile electronic component of claim 1 wherein said projections
extend outward generally parallel to said header allowing said component
to form a surface mount component.
7. The low profile electronic component of claim 1 wherein said header is
made from a plastic material capable of withstanding temperatures of at
least 230.degree. C.
8. The electronic component of claim 1 wherein said first and second core
members are made from a ferrite.
9. The low profile electronic component of claim 1 wherein said projections
have a rectangular cross-section.
10. The low profile electronic component of claim 1 wherein said
projections have an oval cross-section.
11. The low profile electronic component of claim 1 wherein said
projections have a trapezoidal cross-section.
12. The low profile electronic component of claim 1 wherein said pre-wound
coil is a self-supporting coil.
13. The low profile electronic component of claim 1 wherein said recess
extends entirely through said header.
14. A low profile surface mount electronic component comprising:
a flat header having a top and bottom surface and a plurality of edges,
said header having a recess formed in a said top surface;
a plurality of non-conductive projections extending from at least one of
said edges of said header generally parallel to said bottom surface of
said header, said projections being formed from the same material as the
header;
first and second core members forming a core set, said core set being at
least partially disposed within said recess, wherein the first core member
has a first surface and the second core member has a second surface
parallel to and facing the first surface,;
at least one self-supporting coil disposed at least partially within said
core set between the first and second surfaces such that the combination
of the first and second surfaces secure the self-supporting coil in place,
each of said at least one self-supporting coils having at least one wire
lead; and
at least one of said wire leads being wrapped around one of said
projections to form a conductive surface on said projection in order to
form a surface mount terminal for the component.
15. The low profile surface mount electronic component of claim 14 further
comprising a layer of solder disposed on said conductive surface.
16. The low profile surface mount electronic component of claim 14 wherein
each of said projections is positioned perpendicular to the edge from
which it extends.
17. The low profile surface mount electronic component of claim 16 wherein
said projections are parallel to said bottom surface.
18. The low profile surface mount electronic component of claim 14 wherein
at least one of the core members defines an outer surface of the
component.
19. The low profile electronic component of claim 1 wherein at least one of
the core members defines an outer surface of the component.
20. The low profile electronic component of claim 1 wherein said
projections are non-conductive.
21. A low profile surface mount electronic component comprising:
a flat header having a top and bottom surface and a plurality of edges,
said header having a recess formed in a said top surface;
a plurality of non-conductive projections extending from at least one of
said edges of said header generally parallel to said bottom surface of
said header, said projections being formed from the same material as the
header;
first and second core members forming a core set, said core set being at
least partially disposed within said recess;
at least one pre-wound self-supporting coil having top and bottom surfaces
perpendicular to an axis of the coil, said coil disposed at least
partially within said core set with the bottom surface of the coil placed
against the first core member and the second core member placed against
the top surface of the coil to hold the coil in place, each of said at
least one pre-wound coils having at least one wire lead; and
at least one of said wire leads being wrapped around one of said
projections to form a conductive surface on said projection in order to
form a surface mount terminal for the component.
22. A low profile surface mount electronic component comprising:
a flat header having a top and bottom surface and a plurality of edges,
said header having an opening formed through the top and bottom surfaces
of the header;
a plurality of non-conductive projections extending from at least one of
said edges of said header generally parallel to said bottom surface, said
projections being formed from the same material as the header;
a first and second core member forming a core set, said core set being at
least partially disposed within said opening, said opening being sized to
allow the entire core set to be received through the opening;
at least one pre-wound coil disposed at least partially within said coil
set, each of said at least one pre-wound coils having at least one wire
lead; and
at least one of said wire leads being wrapped around one of said
projections to form a conductive surface on said projection in order to
form a surface mount terminal for the component.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to low profile electronic components. More
particularly, the present invention relates to low profile, low cost, high
performance inductor/transformer components.
2. Problems in the Art
There is a need in the electronics industry for low profile, low cost, and
high performance components. Applications such as PCMCIA cards, portable
computers, and other electronic devices with a very limited available
space require manufacturers to supply components such as these.
Low profile electronic components exist in the prior art, but most low
profile designs are centered around "planer" designs formed from alternate
layers of insulating material and copper foil or techniques involving
coils formed on multiple layers of printed circuit board materials. These
prior art designs involve a high cost and also have production
disadvantages.
Other prior art designs for low profile applications include using toroids.
While toroid designs are electrically efficient, they are very labor
intensive to wind and terminate.
Traditional inductor/transformer coil leads are terminated at a separate
metallic terminal which is molded into the header. "Molded-in" terminals
will increase the cost of the header by two to three times. This prior art
design requires a separate soldered connection internal to the component.
These mechanical connections create a point in the component where a
failure can occur, resulting in a product with a lower inherent
reliability.
FEATURES OF THE INVENTION
A primary feature of the present invention is the provision of a low
profile, high performance inductor/transformer component.
A further feature of the present invention is the provision of a low
profile inductor/transformer component having a core mounted at least
partially within the frame of the supporting header.
A further feature of the present invention is the provision of a low
profile inductor/transformer utilizing a self supporting winding,
therefore eliminating the need for a bobbin. A further feature of the
present invention is the provision of a low profile inductor/transformer
component which is bonded together with an epoxy adhesive.
A further feature of the present invention is the provision of a low
profile inductor/transformer component having a ferrite core that can be
formed in a plurality of different shapes.
A further feature of the present invention is the provision of a low
profile inductor/transformer component having wire wrapped terminals,
eliminating the need for a metallic terminal formed in the header.
A further feature of the present invention is the provision of a low
profile inductor/transformer component suitable for use in PCMCIA cards,
portable or notebook computers, DC-DC converter circuits for battery
operated equipment, and other products requiring very high packaging
density.
A further feature of the present invention is the provision of a low
profile inductor/transformer component which can be readily assembled with
automated production techniques.
These as well as other features of the present invention will become
apparent from the following specification and claims.
SUMMARY OF THE INVENTION
A low profile inductor/transformer component of the present invention
includes a header having a plurality of projections, a core set, and a pre
wound coil of wire. The header is formed from a single piece of molded
plastic. A recess is formed in the header for receiving a portion of the
core set. A wire coil is disposed between a lower core half and an upper
core half. The core set is disposed in the recess of the header and the
entire assembly is bonded together with an adhesive. The low profile of
the present design is partly achieved by inserting the core set into the
recess of the header.
Terminals are formed by the projections extending from the header and wire
leads that extend from the wire coil. The wire leads are first wrapped
around the header projections and then emersed in molten solder. The
terminals formed on the header projections provide a vary low cost
termination, and also eliminate the need of molded in metallic terminals
which are present on many prior art headers.
The completed component can be mounted on a printed circuit board in a
number of different ways including being mounted on the PC board surface
and being mounted through the PC board surface. Also, any number of core
set shapes can be used with the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of one embodiment of the present invention.
FIG. 2 shows an enlarged view of one of the terminals formed by a header
projection and a wire lead.
FIG. 3 shows side views of alternative methods for mounting the present
invention on a printed circuit board.
FIG. 4 shows alternative shapes of the ferrite core of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will be described as it applies to its preferred
embodiment. It is not intended that the present invention be limited to
the described embodiment. It is intended that the invention cover all
alternatives, modifications, and equivalences which may be included within
the spirit and scope of the invention.
FIG. 1 shows an exploded view of a component 10 of the present invention.
The component 10 is made by first providing a header 12. The header 12 is
comprised of a single piece of a molded plastic material. The plastic
material is selected to withstand the high temperature involved (greater
than 230.degree. C.) in the component manufacturing process and in the
user's printed circuit board assembly process. The header 12 includes a
plurality of projections 14 that extend from the header 12. The
projections 14 are used in forming component terminals. The header 12
includes a recess 16 which is formed so that a lower core-half 18 can be
received by the recess 16. The header design is very inexpensive to
produce in volume through standard industry molding techniques.
The low profile of the overall component 10 is achieved by extending a
portion of the core set through the header 12. Using this technique, the
maximum height of the component 10 is determined by the required height of
a vertically stacked core set. As shown in FIG. 1, the lower core-half 18
is disposed in recess 16 and extends at least partially through header 12.
The lower core-half 18 is matingly similar to an upper core-half 20 which
is disposed above the lower core-half 18. Disposed between the lower
core-half 18 and the upper core-half 20 is a pre-wound coil 22. An
adhesive 24 is utilized to bond the assembly together after the header 12,
lower core-half 18, upper core-half 20, and coil 22 are assembled. The
component 10 is bonded together with adhesive 24 by covering an area at
the adjoining line of the two core-halves and the joining line between the
lower core-half 18 and the header 12. FIG. 1 also shows an alternative
location for the bonding adhesive 24A when center leg gapped cores are
used in the component 10. Adhesive bonded construction provides a sturdy
component with all the materials bonded together. The bonded construction
will also eliminate the "hum" in the transformer or inductor windings
which is a common complaint.
The basic design of the lower core-half 18 and upper core-half 20 of the
present invention can take on a wide variety of core styles and core
materials. FIG. 4 shows several examples of possible core designs
including, but not limited to, E--E 32, ER 34, ER-I 38, E-I 36, C--C 40,
C-I 42, Pot 44, Tack-Disk 46, and Tack-Cup 48 cores. Any core set that is
capable of being assembled around pre-wound coils could be used in the
present invention.
A variety of materials may be selected for the cores of the present
invention, but the preferred choice will most often be ferrite due to its
inherent properties. The most common applications of the low profile
components 10 are DC-DC converter circuits, which typically require the
choice of a ferrite core material. In addition, ferrite has the capability
of being formed in complex shapes. Also, when used with gapped cores,
ferrite is the most desirable core material for use in a DC-DC converter.
The windings of the coils 22 in the present invention are designed to be
self-supporting, perfectly layered coils in order to provide the best
volumetric efficiency. Also, the traditional bobbin formerly used in
similar designs, is eliminated in order to lower the volume requirements
within the winding window, reduce the height, and to lower the material
cost. The coils 22 of the present invention can be produced on existing
automated equipment which can provide a high volume of production with a
very low labor cost. Individual windings may be designed to utilize the
most desirable wire size depending on the electrical requirements of the
circuit. Previously, automatically wound transformers and the like were
designed with one wire size to obtain the lowest component cost. As shown
in FIG. 1, each coil includes a plurality of wire leads 26 extending from
the coil 22. Each wire lead 26 will be connected to a header projection 14
to form a terminal.
FIG. 2 shows how the terminals of the present invention are formed. Each
wire lead 26 from the pre-wound coil 22 forms a termination on the
appropriate header projection 14. The wire lead 26 is wrapped around the
terminal projection 14 in a "spring" shape. When this "spring" shaped
termination is immersed in molten solder, the wire insulation is melted
from the wire. The "spring" is tinned into a continuous cylindrical shape
which forms the terminal.
The wire wrapped terminals may be formed over header projections 14 that
have a multitude of shapes. For example, the header projections could have
a circular, oval, rectangular, square, trapezoidal, or any other cross
section. Different shapes of projections 14 provide different advantages
in presenting different profiles to the automated winder and to the
printed circuit board surface that the component is mounted upon.
Typically, the number of terminals on a component may vary from four to
twelve on components incorporating this basic style of design. Of course,
other designs may include a different number of terminals.
The wire wrapped terminals of the present invention allow for the use of a
low cost header and also provide a very lost cost termination. The cost of
the termination is low since a separate metallic terminal does not need to
be molded into the header 12. The cost of a "molded-in" terminal will
increase the cost of a header significantly. These wire wrapped terminals
also have the advantage of eliminating one mechanical connection for each
terminal on the component 10. This is because on a traditional molded-in
terminal, a connection must be made between the coil lead and the molded
metallic terminal.
The inductor/transformer design of the present invention with the header
12, windings 22, core set 18 and 20, and terminations can be readily
assembled with automated production techniques. The winding 22 can be
automatically wound on existing winding equipment. The header 12, core set
18 and 20, and winding 22 can be semi-automatically assembled on automated
equipment. The bonding adhesive 24 can be applied through automatic
dispensing equipment. The terminations can also be automatically completed
with equipment that is similar to traditional "wire wrap" equipment.
The design of the present invention allows the component 10 to be mounted
on a printed circuit board (PCB) 28 in a variety of ways. FIG. 3 shows
some examples of different mounting configurations. For example, the
component can be mounted on the PCB surface (FIG. 3A), through the PCB
surface (FIG. 3B), or in an alternate component form projecting through
the PCB with the terminal portions of the component mounted on either
surface of the PCB (FIG. 3C, 3D).
When the present invention is applied to a transformer, a desirable
performance, with truly isolated windings, is readily achieved with this
component design. Very few manufacturers are currently offering truly
low-profile transformers that can be used in the DC-DC converter circuits
of PCMCIA Type II applications. Isolated windings offer a significant
advantage since both positive and negative voltages need to be generated
from a single voltage source. The degree of isolation may be increased by
coating the cores with an insulating material such as paylene and by
adding insulating "washers" of dielectric material such as mylar between
wound coils during assembly.
The present invention is designed to have a maximum volumetric efficiency,
a very low profile, and a relatively high current handling capacity.
Preferably, the components of the present invention are manufactured with
automated equipment and have a low cost of raw materials. The materials
are carefully selected to withstand the rigorous environment encountered
by surface mount components during their manufacturing process and their
product life cycle.
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